It’s because of a little thing called “tradition”. Now I’m not one that thinks all traditions should be adhered to, but if you’re part of a “traditional” gathering, and especially if you’re asked to provide entertainment for said “traditional” gathering, then you shouldn’t be an ass and try to use that venue to “show off your chops”.

The audience, (or most of it), wants to sing along, and they can’t if you try to treat the song as some improvisational jazz or gospel song.

Shucks, if you can pull off this song in the “straight” melody, you’ve accomplished quite a bit.